<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link rel="stylesheet" href="./css/3.css">
</head>

<body>

  <div class="row" style="background-color: antiquewhite;">
    <div class="col col-md-3 col-sm-6 col-xs-2">1</div>
    <div class="col col-md-3 col-sm-6 col-xs-10">2</div>
    <div class="col col-md-3 col-sm-6 col-xs-10">3</div>
    <div class="col col-md-3 col-sm-6 col-xs-2">4</div>
  </div>

  <div class="row row-y-flex-end row-x-space-around" style="height: 100px;">
    <div class="col col-1" style="height: 50px;">1</div>
    <div class="col col-2" style="height: 30px;">2</div>
    <div class="col col-3" style="height: 60px;">3</div>
  </div>

  <div class="row">
    <div class="col col-6">1</div>
    <div class="col col-6">2</div>
  </div>

  <div class="row">
    <div class="col">1</div>
    <div class="col">2</div>
    <div class="col">3</div>
  </div>

  <div class="row">
    <div class="col col-6">6</div>
    <div class="col col-6">
      <div class="row">
        <div class="col col-6">1</div>
        <div class="col col-3">2</div>
        <div class="col col-3">3</div>
      </div>
    </div>
  </div>

  <div class="row">
    <div class="col col-xs-4">col-xs-4</div>
    <div class="col col-xs-8">col-xs-8</div>
  </div>

  <div class="row">
    <div class="col col-sm-10">col-sm-10</div>
    <div class="col col-sm-2">col-sm-2</div>
  </div>

  <div class="row">
    <div class="col col-lg-8">col-lg-8</div>
    <div class="col col-lg-4">col-lg-4</div>
  </div>






</body>

</html>